In fact, this will be my first fish ever. So you can imagine I'm feeling really overwhelmed right now at the discovery that fish need way more than just a tank of water and a plastic tree in order to live.

So today I bought this handsome little devil, Monty!

And along with him I bought this tank and food that were both recommended to me by the store clerks, who also told me that I didn't need a filter and that betta were able to live in conditions without one. But after coming here I feel as if they were wrong. I also bought a plastic tree which none of them bothered to tell me that plastic could harm betta fins.

The store clerks told me that I should fill the tank up with room temperature tap water and wait 12 hours before putting Monty into it. It really pains me to watch him in the container of water with little to no room and I'm just wondering if they were correct? The tank of water has major bubbles in it and I'm also wondering if that should be happening.

And lastly, I noticed that Monty has black in his gills.
Does anyone know what has caused this? I've never had a fish, let alone a betta and I feel as though I have been left out in the dark. I really want Monty to thrive and live a happy life and I feel incapable of giving him that at this point. Any advice is majorly appreciated at this point.

Well, I'll tell you what I know, but I am somewhat of a new Betta Mom, too. :)

Bettas need at least 1-2 gallons (recommended), and if you don't have a filter, that's fine, just more water changes. 1-2 a week for those sizes, like 1 50% and a 100% on top of that.

I know they need a heater (adjustable for sure, 100%, got one without adjustable, and it didn't do well...) and the ideal temp. 78-80 Fahrenheit.

People recommend Omega One or some others I can't think of...

The gills don't look bad, just like the color. But like I said, I am not an expert. I hope I helped, at least a little! By the way, super cute fish!

I am definitely going to buy a heater tomorrow. His gills just look very black and utterly gross so I got concerned. And thank you! I thought he was so beautiful at the store I was surprised no one had picked him up yet.

My recommendations for food would be to, ditch the current food and get either New Life Spectrum pellets or Omega One pellets. Pellets are better for the fish, and help keep the tank cleaner.

As for the filter, it's not really needed. I do not have any of my fish in filtered tanks. However, a heater is necessary and a thermometer (preferably two, so you can compare temps to ensure the tank stays between 76-82).

The tank looks like a .5 g. I would recommend upgrading to at least a 2.5 g tank. The smaller the tank the more frequent the water changes, and just the less stimulating the environment.

The picture you have of Monty he looks fine. That's just his coloring.

ETA: Is the plastic soft? If it is soft it should be okay. I have plastic plants but they are all rounded edges and soft.

What size is the tank you have now? Bettas need a 2.5 gallon minimum with 5 gallons being preferable and the more the better. I suggest you go back to PetCo tomorrow and return the tank you have (it looks a bit small) and get something a bit bigger. Walmart has a nice 5 or 10 gallon kit for around $30. Most tank kits don't come with a heater, but they are essential. Adjustable heaters are always prefered, but preset ones can work too. Make sure to grab a thermostat to keep an eye on the temperature. Ones with mercury and go inside the tank are generally better than the ones that you stick on the outside.

When looking for decor you'll want to get silk plants. They won't rip or tear Monty's fin. Bettas also usually like caves to his in, but make sure the whiles aren't too small.

You might want to try and return that food and get something of a higher quality like New Life Spectrum or Omega One Betts Buffet. You can also get frozen bloodworms, brine shrimp, or daphnia to give your betta once a week as a treat. They do sell freeze dried foods, but they aren't nearly as good and can be hard for bettas to digest.

For your water you will have to wait now for 12 hours for the clorine to exit your tank. When you're at the store pick up a bottle of SeaChem Prime or API Stress Coat Water Conditioner. When you're doing water changes you'll need to treat your water to get rid of the chlorine that can kill your fish.

Unfortunately, I also can't help you with his gills as I'm no good at betta illnesses, but I'm sure someone will come along soon that can help you with that. Good luck with him

As you see, you will get a lot of contradictory information, even here. You will have to take everything with a grain of salt and figure out what is best for you and your fish.

All we can do is recommend from our own experience/research :)

I will give you my opinions from my 20 years of experience and research.. some things may have already been covered, some things will contradict what others have said. So take what you will and do what you think is best and you'll be fine.

Tank size - anything above 1 gallon is fine. It all depends on the room you have and money available to spend. But 1 gallon and up can be a perfect home for them. That is really the minimum size I recommend to people who are just starting out and/or are just having pet fish.

A 1-4 gallon requires the exact same care when it comes to water changes. It will depend on whether or not the tank has a filter or live plants.
Based on your set up, no filter nor live plants it is recommended to do either 1 50% and 1 100% per week, or 1 100% every 5 days. Either of those will keep the tank clean without being too sterile.
If you get a tank with a filter then it would be 2 50% per week or 1 50% every 5 days. I say the 5 days recommendations as I have found that the water is pretty much the same as if doing it twice a week.
If you get one with a filter make sure to use a siphon to vacuum out the gravel to remove the waste - the smaller the tank the smaller the vacuum you will want to use.

A 5+ gallon tank will require a bit different - with a filter you are looking at 1 50% per week with the siphon. Without a filter it will be 1 50% per week and 1 100% per month with the siphon. Live plants will change the %.

Keep in mind too clean can cause health problems just like not being clean enough, but in different ways.

As for a heater - it depends on the tank.. Walmart has a Tetra one that is preset that works in tanks from 1-10 gallons - it says 2-15 on the box, but at 10 gallons it only reaches to 76/77 so I would not advise it for anything larger than a 10 gallon. It is preset and works just fine in 10 gallons and under.
Heaters that you can manually adjust temperature is nice, but it's not necessary for the basic pet betta/fish tank.
For tanks 1-4 gallons I would recommend a 25 watt heater, for tanks 5-10 gallons I would go with a 50 watt.. anything larger you can ask us for recommendations.

Decorations - Bettas love large leafy silk plants that are tall, they love to lay on leaves close to the surface to sleep on. Many also love caves.. I have an old one that sleeps in his cave every night and it's pretty cute that in the morning I have to knock on his tank to wake him up for breakfast.. sometimes he'll peek his head out of the cave and then go back in for a few minutes of extra sleep lol. A cave isn't necessary, but it's an option. You want to avoid plastic plants that are sharp and pointy.. there are some soft plastic plants, but you will have to use your own judgement. Think of their fins like wet tissue paper.

Keep the cup he came in and use it to remove him for large water changes - eventually it will get easier to scoop them out of the water. Some will get used to it, others will still run away. Just gotta learn to be quick. If he gets wise to what you are wanting to do, just toss in a pellet or two and entice him back up to the top and scoop from behind him while he is busy eating. He'll hate you, but it takes away the risk of tearing his fins on a net.

Most of your water conditioners nowadays work instantly and you do NOT have to wait to place them in it. Way back when it was recommended, but in the last couple decades you really don't have to. I would suggest adding the conditioner in at the same time you are adding in new water rather than wait until after the water is in the tank and then put in the conditioner. Adding it at the same time as adding the water will help disperse it throughout the tank quicker. So no worries on waiting.. I have never aged my water prior to adding in my fish and have had no health/deaths due to that. Even my sensitive newborn betta fry I don't use aged water on and I have no problem. So no worries on that.

As for his gills.. it looks normal. Some have black gills.. sometimes bettas will change colors shortly after they adjust to their new home. He may become darker or lighter, colors may change some. He has a black ring around his eyes - which makes me believe even stronger that it's just his unique coloration. It may change in time, may become lighter.. but either way there is no disease that I am aware of that creates black gills.

Good luck with your little guy! He is a cutie.. and you will be fine in caring for him :) It's not always the easiest/smoothest the first time owning fish, but eventually you'll be more confident and it'll be easier to care for them.. and you won't stop at just one once you see their personality :)

Today I bought a 10 gallon tank just because and the heater doesn't seem to be working as well as the filter seems to be too strong (or at least that's my opinion but my friend said he looks fine.) I appreciate all the responses!

The strength of the filter shouldn't effect the heater. I haven't read through the whole topic, but do you have a thermometer? It's very important because heaters can malfunction and aside from feeling the water, you may not notice.